1. Field of Invention
This invention pertains to a process of foaming or frothing asphalt, and products made by the process.
2. Prior Art and Other Considerations
Foamed asphalt can be used to create three-dimensional profiles in shingles, and to reduce the density of protective (e.g., moisture resistant) coatings or boards.
Heretofore, asphalt was frothed, or foamed, by the mechanical addition of inert gasses, generally air. Historically the addition of inert gases has required expensive equipment and costly processing methods. For example, U.S. Pat. No. 4,399,186 teaches the use of mechanically mixing an inert gas with molten asphalt either by utilizing high pressure pumps or high shear mixers.
Accordingly, it is an object of the present invention to provide an efficient and economical process for frothing, or foaming, asphalt.